This application claims priority based on patent applications No. 2000-230095 and No. 2000-230624 filed in Japan, the contents of which are incorporated herein by reference.
Recently, high-luminance light emitting elements, such as light emitting diodes (hereinafter, occasionally abbreviated to LEDs), have been developed for each of RGB that stands for red, green, and blue known as primary colors of light, and the production of large-scale self-luminance full color displays is being started. Further, various illumination such as an intelligent illumination which illuminates articles etc. with momentary changes in various color or brightness is being developed. Among others, LED displays have characteristics that they can be lightweight and slimmed-down, and that they consume less power, etc. Hence, a demand for LED displays as large-scale displays that can be used outdoors has been sharply increasing. Also, the use of LED displays has been diversified, and there has been a need for a system flexibly adaptable to various applications, such as large-scale TV sets, advertisements, billboards, traffic information, stereoscopic displays, and illuminations.
Generally, a dynamic driving system is employed in an LED display driving system. For example, in the case of an LED display constituted by M rows×N columns dot matrix, anode terminals of LEDs 11a disposed in each row, which are lighting elements, are commonly connected with one common source line 12, and cathode terminals of LEDs disposed in each column are commonly connected with a current line 13 of each column. Each of the current lines 13 can be connected with a constant-current source 14a, respectively. The common source lines 12 of M rows are turned ON in a predetermined period one after another, the LED driving current being impressed to the current lines 13 of N columns based on image data corresponding to the line turned ON. Accordingly, the LED driving current is impressed to the LEDs 11a of each pixel corresponding to the image data, and therefore, an image is indicated.
In the case of a large-scale LED display disposed in the outdoors, generally the LED display is assembled by a plurality of LED units to constitute spontaneous shape or size with relative ease, each of the LED units indicating each part of whole image data. LED units have light emitting diodes, which are one set of RGB, disposed on a substrate in a matrix shape, wherein each of the LED unit works as the LED display mentioned above similarly. In large-scale LED display units, many LEDs are employed, for example, in the case of 300 in longitude×400 in width, LEDs corresponding to 120,000 pixels are employed.
FIG. 1 is an exemplary explanatory diagram showing a flow of a signal in the driving circuits of each of the LED units mentioned above. An image indicating apparatus shown in FIG. 1 has a display section 1 having a plurality of lighting elements in a matrix shape, a vertical driving section 2 impressing voltage to each line of the display section 1 selectively and changing the line one after another in a vertical direction, and horizontal driving sections 3 corresponding to a plurality of columns providing each column in the selected line of the display section 1 with a driving current based on indicating data.
In the case of luminance gradation control by a pulse modulation system, gradation data (DATA) is input to the horizontal driving section 3 of the display apparatus. The vertical driving section 2 changes each line of the display section 1 one after another. With synchronizing image indicating a start of every line corresponding to each row of the display section 1, a lighting control signal input to a lighting control section 15 becomes in active. With synchronizing the lighting control signal, a latch signal (LATCH) to retain data of the image is input. The gradation data of each color is captured into shift resisters disposed in a memory section 17 of the LED driving section (LED Drivers 1–N) constituting the horizontal driving section 3, then shift clock (SCLK) synchronizing with the data is input to control sections 18 during an active period of the data. For example, the LED driving sections are constituted by the horizontal driving sections 3 having a predetermined number of constant-current outputs as driver ICs, which are modularized into ICs.
Each constant current driving section 14 disposed in the horizontal driving section 3 provides the driving current of each line provided to the display section 1. With synchronizing vertical driving section 2 control address (common control address) with the lighting control signal, a control signal synchronized is input from decoder 16, and accordingly, the constant current driving section 14 of the horizontal driving sections 3 connected with each column provides the driving current. The vertical driving section 2 changes each row of the display section 1 one after another to indicate.
In this driving circuit, with increasing pixel number of the lighting elements to be gradation-controlled simultaneously, many LED driving circuits driving the lighting elements are required. Further, each data of a signal group for driving control such as lighting control signal, gradation reference clock, gradation data, latch signal, shift clock or the like is required to be provided for each driver IC constituting each of the LED driving circuits.
However, the driving circuit mentioned above has a disadvantage due to an increase in the number of the lines of input signal interfaces for lighting control. Especially, nowadays a number of gradation is multiplied, and according to a gradation-multiplication of data, a width of gradation data bus is increased such as to 8 bit, 10 bit, and 12 bit. Furthermore, the driving circuit mentioned above needs a data signal group corresponding to 3 colors, which are RGB. A line pattern should be disposed among the driver ICs according to many lines, and therefore, the number of pattern lines is increased significantly, so that a driving substrate 42 becomes a complicated hand-wired multi-layered device having a high-cost. When signal terminals of the driver ICs are increased, their content become high and they occupy a majority of mounting content, and further, the number of terminals of connectors for the connecting interface is increased, and the size of the connectors become bigger, so that it has a disadvantage that the size of the substrate is further increased.
Further, various clock signals such as shift clock, gradation reference clock or the like are required to be provided for all of the driver ICs. Therefore, pattern hard-wire turning around in the same indicating apparatus causes a problem to occur of pulse deformation by reflection of the signal or variation of pulse width. Especially, with gradation-multiplication increasing, a frequency of the gradation clock should be higher, so that its influence becomes higher in circuit performance, and an influence to the data bus by radiation noise cannot be ignored. Therefore, although a PLL circuit can be employed in the driver IC to provide low frequency clock or the like, for example, this method makes the driver IC's cost higher, and has a problem not to be able to perform gamma-correcting by modulation of the gradation reference clock.
Furthermore, according to the driving circuit mentioned above or a data transferring system performing light control, there is a problem that an amount of transferring, and sequence of information, are different corresponding to a vertical driving duty ratio. When a connecting constitution of a plurality of driving circuit groups and lighting elements is changed, a transferring sequence of information transferred from an external control section should be changed also. Therefore, the control circuit is required to be re-designed and assembled. Further, an arrangement of the driving section or pattern hard-wire or the like designed to prevent signal deformation in the lighting device effectively cannot be optimized by changing the constitution, and there is a problem that matching between the external driving section is lost.
In addition, in a method disposing each driver IC, which is the horizontal driving section, in a transferring order of the data, the data is required to be transferred to each driver IC as individual information corresponding to the connecting order of the driver ICs one after another. However, this method requires determining the arrangement of the driver ICs before assembling the driving circuit.
On the other hand, elongating the signal line also has a problem. In related art, a signal flow in each row of a display—display section is constantly in one direction. For example, in a circuit constitution connecting each driver IC in a Z-shape as shown in FIG. 21, the signals are transferred from a left end to a right end, and then turns back to the left end in the next row. Therefore, the driver IC positioned at the right end is required to be connected with the driver IC positioned at the left end, so that there is a problem that elongating the signal line complicates hard-wire. Further, there is a problem that elongating the signal line causes reflecting deformation of the signal among the terminals, and that turning around and deformation of the signal generates noise and so on.
Besides, in Japanese laid-open patent publication No. H11-126047, the content of which is incorporated herein by reference, there is disclosed an LED indicating apparatus transferring data formatted in an ATM packet format to each LED unit, wherein the LED unit has a means for storing identification information added to each LED unit, and a comparing means for comparing the data from a control means with the identification information of each LED unit to perform a receiving process by selecting the data for its own therein, as an LED indicating apparatus and a method thereof. Similarly, there is disclosed an LED indicating apparatus assigning identification information to each LED unit automatically in Japanese laid-open patent publication No. 2000-221934, the content of which is incorporated herein by reference. In addition, the content of Japanese patent applications No. 2000-199420 and No. 2000-121649 filed in Japan, which are the prior filed applications, are incorporated herein by reference.
To solve the problem mentioned above, this invention further improves upon the prior applications. It is an object of the invention to provide a driving circuit etc., in which a simplifying circuit constitution with a smaller number of control signal lines or data lines provided to a driver IC makes the driver IC and a driving circuit board low-cost, while performing image indicating in high quality.
Another object of the present invention is to provide a display apparatus, which can adapt corresponding to a variation of disposition of driving sections in a display device or connecting formation form flexibly, with defining configuration of various data transferred to horizontal driving sections from a driving control section without influence according to a deference of a driving system of the indicating devices by disposing a communicating section communicating data in a common configuration to the horizontal driving sections in the display apparatus. Still another object of the present invention is to provide a driving circuit for a display apparatus etc., which is not required to transfer data in a signal line connecting order one after another by determining a destination of the data to be transferred, and therefore, horizontal driving sections can be connected relatively in a flexible manner.